The curing of unsaturated polymers and grafting onto unsaturated elastomers is well known in the art. Such prior art produces either a non-rubbery product or product not obtainable by the easily processable mixes of the present invention.
For example, U.S. Pat. No. 3,791,655 discloses a method for preparing a hard rubber compound by grafting a carboxamide onto polybutadiene in the presence of a free radical initiator. Monomers such as styrene and vinyl toluene were used to crosslink polyvinyl chloride in U.S. Pat. No. 3,275,714, but here, as in the above-mentioned patent, the product is non-rubbery and the polymer does not contain randomly distributed sites of conjugated olefinic unsaturation. The aforesaid Baldwin et al application discloses graft curing of monomers, but the monomer must be soluble in the elastomer. The present invention overcomes this problem by providing a technique whereby the monomer may be efficiently and effectively dispersed into the elastomeric polymer. Thus, monomers generally including monomers considered not normally compatible with and soluble in the elastomer and mixtures of monomers may be used as free radical crosslinking agents in accordance with the present invention.